TW201417475A - Signal peak detector and method and control IC and control method for a PFC converter - Google Patents

Abstract

A control IC for a PFC converter has a pin for detecting a AC component and a DC component of an input signal. The control IC comprises a signal peak detector for detecting a peak value of the input signal on the pin so as to obtain the DC component of the input signal. Since the AC component and the DC component of the input signal can be obtained through the same pin, the amount of pins can be decreased.

Description

Signal peak detector and method, and control IC and control method of PFC converter

The present invention relates to a signal peak detector and method, and more particularly to a signal peak detector and method for use in a Power Factor Correction (PFC) converter to reduce the number of pins.

Current PFC converters usually need to obtain the AC information of the input signal and the DC information to achieve various applications, such as using the AC information to obtain a current proportional to the input signal waveform, detecting the valley value of the input signal, and determining the total harmonic distortion. (Total Harmonic Distortion; THD) improves the trip point, etc., and the DC information can be used to determine the size of the input signal, to achieve a brown in/brown out protection. Traditional methods of detecting DC information are usually obtained by detecting the peak or rms value of the input signal.

1 shows a control integrated circuit (IC) 2 of a conventional PFC converter. The AC voltage Vac supplied to the PFC converter is rectified via the bridge rectifier 4 to obtain an input signal Vin, and the voltage dividing circuit 6 divides the input signal Vin to generate an input signal. Vd to the pin MULT of the control IC 2, the control IC 2 can obtain the exchange information of the input signal Vin by the input signal Vd on the pin MULT. The PFC converter uses the signal peak detector 8 to detect the peak value of the input signal Vd to obtain the DC information of the input signal Vin. In the signal peak detector 8, an ideal diode composed of a diode and an operational amplifier. 10, the input signal Vd is supplied to the capacitor C1, thereby generating the peak signal Vpeak. The conversion circuit 12 obtains the DC information of the input signal Vin according to the peak signal Vpeak, and the resistor Rff connected in parallel with the capacitor C1 serves as a discharge path for the capacitor C1 to be slowly discharged. However, the traditional method of detecting DC information needs The large capacitor C1 is required to stabilize the peak signal Vpeak, and the large capacitor C1 cannot be fabricated in the control IC 2. Therefore, another pin VFF is required to externally mount the large capacitor C1, that is, the conventional PFC converter requires two pins. MULT and VFF are used to obtain the exchange information and DC information of the input signal Vin.

In addition, the method of using the capacitor C1 to obtain the peak signal Vpeak has a slower transient response when the peak value of the input signal Vin changes from high to low. Specifically, referring to FIG. 2, at time t1 to t2, the input signal Vin changes from a low peak to a high peak, and the peak signal Vpeak on the capacitor C1 quickly rises from the first level VL1 to the second level VL2, but When the input signal Vin changes from a high peak to a low peak, as shown by time t3 to t4, since the capacitor C1 cannot be quickly discharged, the peak signal Vpeak needs to pass through several cycles TP before falling from the second level VL2 to the first. The level VL is the period of the input signal Vin, so the signal peak detector 8 of FIG. 1 has a slower transient response when the peak value of the input signal Vin changes from high to low.

In order to reduce the number of pins, in some applications, the PFC converter may abandon the acquisition of communication information and only obtain DC information. Figures 3, 4 and 5 show a detector for detecting DC information when no communication information is obtained. 3 shows a conventional square root detector 14 comprising a resistor R3 and R4 and a capacitor C1 for obtaining a rms value Vrms of the input signal Vin to the control IC 2, and the rms value Vrms has a DC information of the input signal Vin. Therefore, the control IC 2 can obtain the DC information of the input signal Vin. 4 shows another signal peak detector 8, which includes a capacitor C1, resistors R3, R4, and Rff, and a diode D1. The resistors R3 and R4 divide the input signal Vin to generate an input signal Vd via a diode. D1 charges the capacitor C1 to generate the peak signal Vpeak to the control IC 2, so that the control IC 2 obtains the DC information of the input signal Vin, and the resistor Rff connected in parallel with the capacitor C1 serves as the discharge path for the capacitor C1 to be slowly discharged. In the signal peak detector 8 of FIG. 4, the forward bias of the diode D1 causes an error between the peak signal Vpeak and the peak value of the input signal Vd. To eliminate this error, the anode of the diode D1 can be eliminated. A diode D2 is added between the resistor R4, as shown in FIG. However, the detectors shown in FIG. 3, FIG. 4 and FIG. 5 also have a problem of slower transient response when the peak value of the input signal Vin changes from high to low.

US Pat. No. 6,731,230 teaches a method for detecting a signal peak, which detects an input signal and generates an output peak signal. When the input signal is rising, if the output peak signal is smaller than the input signal, the output peak signal is increased at a faster speed. During the falling of the input signal, in order to maintain the output peak signal at the peak voltage level of the input signal, the reference voltage is used to detect the input signal, and when the input signal is lower than the reference voltage by more than a plurality of preset working clocks, the output peak is blocked. The signal drops as the input signal drops. However, this detection method also has a problem of a slower transient response when the peak value of the input signal changes from high to low.

One of the objects of the present invention is to provide a control integrated circuit and a control method for a PFC converter, which use a single pin to obtain AC information and DC information of an input signal.

One of the objects of the present invention is to provide a signal peak detector and method for use in a PFC converter.

One of the objects of the present invention is to provide a signal peak detector and method having a fast transient response.

According to the present invention, a control integrated circuit of a power factor correction converter includes: a pin receiving input signal for the control integrated circuit to obtain AC information of the input signal; and a signal peak detector connected to the pin, Detecting the peak value of the input signal produces an output peak signal of the DC information having the input signal. The signal peak detector includes: the first comparator generates a comparison signal when the input signal is greater than an internal peak signal; the first counter increases the output value according to the comparison signal, and resets the reset signal according to the reset signal Counting value; the first digital analog converter converts the count value into the internal peak signal; the storage unit acquires and stores the count value from the first counter according to the sampling signal; the second comparator is lower than a reference voltage in the input signal And generating the sampling signal, and generating the reset signal after the sampling signal ends; and the second digital analog converter generating the output peak signal according to the count value stored in the storage unit. The control integrated circuit can obtain the AC information and the DC information of the input signal by using a single pin, thereby reducing the number of pins. The first counter of the signal peak detector re-counts every cycle of the input signal so that the output peak signal can be immediately adjusted to the target standard in the next cycle, so that the peak value of the input signal changes from low to high. The signal peak detector has a fast transient response when either going from high to low.

According to the present invention, a control integrated circuit of a power factor correction converter includes: a pin receiving input signal for the control integrated circuit to obtain AC information of the input signal; and a signal peak detector connected to the pin, Detecting the peak value of the input signal produces an output peak signal of the DC information having the input signal. The signal peak detector includes: the comparator compares the input signal and an output peak signal to generate a rising signal or a falling signal; the counter is based on the rising signal The number or down signal increases or decreases the count value of its output; and the digital analog converter generates the output peak signal of the DC information having the input signal based on the count value. Wherein, the count value is increased by a first frequency, and is decreased by a second frequency lower than the first frequency. The control integrated circuit can obtain the AC information and the DC information of the input signal by using a single pin, thereby reducing the number of pins.

According to the present invention, a signal peak detector includes: a first comparator that generates a comparison signal when an input signal of the signal peak detector is higher than an internal peak signal; and the first counter boosts the output according to the comparison signal. Counting value, and resetting the count value according to the reset signal; the first digital analog converter converts the count value into the internal peak signal; the storage unit acquires and stores the count value from the first counter according to the sampling signal; The second comparator generates the sampling signal when the input signal is lower than a reference voltage, and generates the reset signal after the sampling signal ends; and the second digital analog converter converts the count value stored in the storage unit into The output peak signal associated with the peak value of the input signal. The first counter of the signal peak detector re-counts every cycle of the input signal so that the output peak signal can be immediately adjusted to the target standard in the next cycle, so that the peak value of the input signal changes from low to high. Or from high to low, the signal peak detector has a fast transient response.

According to the present invention, a signal peak detector includes: a comparator for comparing an input signal of a signal peak detector and an output peak signal to generate a rising signal or a falling signal; and a counter connected to the comparator, according to the rising signal or falling The signal is used to increase or decrease the count value output by the digital signal converter; and the digital analog converter is connected to the counter and the comparator to convert the count value to generate the output peak signal. Wherein the count value is raised at a first frequency to be lower than the second frequency of the first frequency The rate is lowered.

According to the present invention, a control method for a power factor correction converter includes the steps of: receiving an input signal by a pin to obtain an exchange information of the input signal; providing a count value; converting the count value to generate an internal peak signal; When the signal is greater than the internal peak signal, the count value is raised; when the input signal is less than the reference voltage, the count value is stored; the output peak signal of the DC information having the input signal is generated according to the stored count value; and is stored After the count value, the count value is reset. The control method uses the single pin to obtain the AC information and the DC information of the input signal, so that the number of pins can be reduced, and each cycle of the input signal is re-counted so that the output peak signal can be immediately adjusted to the next cycle. Target level, so the control method has a fast transient response regardless of whether the peak value of the input signal changes from low to high or from high to low.

According to the present invention, a control method for a power factor correction converter includes the steps of: receiving an input signal by a pin to obtain an exchange information of the input signal; providing a count value; and converting the count value to generate a DC information having the input signal Output peak signal; when the input signal is greater than the output peak signal, the count value is raised by the first frequency; and when the input signal is less than the output peak signal, the second frequency is decreased by less than the first frequency The count value. The control method uses a single pin to obtain the AC information and DC information of the input signal, so the number of pins can be reduced.

According to the present invention, a signal peak detecting method for detecting a peak value of an input signal to generate an output peak signal includes the steps of: providing a count value; converting the count value to generate an internal peak signal; and when the input signal is greater than the internal peak signal, adjusting Raising the count value; storing the count when the input signal is less than a reference voltage a value; generating the output peak signal according to the stored count value; and resetting the count value after storing the count value. The signal peak detection method is re-counted every cycle of the input signal so that the output peak signal can be immediately adjusted to the target standard level in the next cycle, so that the peak value of the input signal changes from low to high or from high to low. The control method has a fast transient response.

According to the present invention, a signal peak detecting method for detecting a peak value of an input signal to generate an output peak signal includes the steps of: providing a count value; converting the count value to generate the output peak signal; and when the input signal is greater than the output peak signal, The count value is raised at a first frequency; and when the input signal is less than the output peak signal, the count value is adjusted at a second frequency less than the first frequency.

Figure 6 shows an embodiment of the control IC 2 of the present invention. Referring to FIG. 1, the AC voltage Vac is rectified by the bridge rectifier 4 to obtain an input signal Vin, and the voltage dividing circuit 6 divides the input signal Vin to generate an input signal Vd to the pin MULT of the control IC 2 for controlling the internal circuit of the IC 2. Get the communication information of the input signal Vin. In FIG. 6, the control IC 2 includes a signal peak detector 20 that uses the pin MULT to detect the peak value of the input signal Vd to generate an output peak signal Vpeak for obtaining the DC information of the input signal Vin, which is obtained by using the same pin MULT. The communication information and the DC information of the signal Vin are input, so that the control IC 2 of the present invention can reduce the number of pins. In the signal peak detector 20 of FIG. 6, the first comparator 22 is connected to the pin MULT for comparing the input signal Vd with the internal peak signal Vpeako. When the input signal Vd is higher than the internal peak signal Vpeako, the first comparator 22 The comparison signal Sc is generated, the first counter 26 raises the count value COT according to the comparison signal Sc, and the first digital analog converter 28 counts the count value COT. Converted to the internal peak signal Vpeako, the second comparator 24 is connected to the pin MULT for comparing the reference voltage Vref and the input signal Vd, and sequentially generates the sampling signal S/H and resetting when the input signal Vd is lower than the reference voltage Vref. The signal reset is respectively given to the storage unit 29 and the first counter 26. The storage unit 29 includes a switch SWA and a second counter 30. The second counter 30 is connected to the first counter 26 via the switch SWA. When the sampling signal S/H is turned on, the SWA is turned on. The second counter 30 acquires and stores the count value COT from the first counter 26, and the second digital analog converter 32 generates the output peak signal Vpeak based on the count value COT stored in the second counter 30. The operating frequencies of the first comparator 22 and the second comparator 24 are determined by the operating clock CLK.

Figure 7 shows a waveform diagram of the signal in Figure 6. Referring to FIG. 6 and FIG. 7, when the input signal Vin rises, as shown in time t1 to t2 of FIG. 7, the input signal Vin is greater than the internal peak signal Vpeako, so the comparison signal Sc is output under the control of the operating clock CLK of the first comparator 22. The first counter 26 is incremented by the count value COT, thereby increasing the internal peak signal Vpeako, and the internal peak signal Vpeako thus rises with the input signal Vin. When the input signal Vin reaches the peak value, it starts to fall. As shown by time t2, the input signal Vin is less than the internal peak signal Vpeako during the falling period, so the first comparator 22 stops outputting the comparison signal Sc, and the count value COT is no longer rising. The value COT remains unchanged and the internal peak signal Vpeako remains unchanged. When the input signal Vin is smaller than the reference voltage Vref, as shown by time t3, the second comparator 24 first generates the sampling signal S/H on switch SWA, so that the second counter 30 acquires and stores the count value COT, and the second digital analog converter 32 further generates an output peak signal Vpeak according to the count value COT stored in the second counter 30. After the sampling signal S/H ends, the second comparator 24 The reset signal Reset is sent to the first counter 26 to reset the count value COT, and the internal peak signal Vpeako is thus reset. The signal peak detector 20 recounts the count value COT at the beginning of each cycle to detect the peak value of the input signal, and determines the output peak signal Vpeak of the next cycle according to the obtained count value COT, so the peak value of the input signal Vin is From low to high or high to low, the signal peak detector 20 has a fast transient response.

More specifically, referring to FIG. 6 and FIG. 8, when the period TP1 of the input signal Vin is input, the peak value of the input signal Vin is higher than the previous period. At the beginning of the period TP1, the count value COT is re-counted to obtain the input signal Vin. The peak-related count value COT, when the next period TP2 of the period TP1 starts, the second counter 30 stores the count value COT obtained in the period TP1 to generate an output peak signal Vpeak corresponding to the peak value of the input signal Vin in the period TP1. In contrast, at the period TP3, the peak value of the input signal Vin is lower than the previous period TP2. At the beginning of the period TP3, the count value COT is re-counted, and at the beginning of the next period TP4 of the period TP3, the second counter 30 is stored in the period. The count value COT obtained by TP3 is used to generate an output peak signal Vpeak corresponding to the peak value of the input signal Vin in the period TP3. As can be seen from FIG. 8, regardless of whether the peak value of the input signal Vin is changed from low to high or from high to low, the signal peak detector 20 can adjust the output peak signal Vpeak to the target standard in only one cycle, so that it has a fast Transient response.

FIG. 9 is another embodiment of the signal peak detector 20, which also detects the peak value of the input signal Vd by detecting the peak position of the input signal Vd to generate the output peak signal Vpeak for obtaining the DC information of the input signal Vin. Use the same pin MULT to get the communication information and DC resources of the input signal Vin Therefore, it can reduce the number of feet. The signal peak detector 20 of FIG. 9 includes a clock generator 40, a comparator 42, a counter 44, and a digital analog converter 46. The comparator 42 is connected to the pin MULT of the control IC 2 for comparing the output peak signal Vpeak and the input signal Vd to generate the rising signal UP or the falling signal DN. When the input signal Vd is greater than the output peak signal Vpeak, the comparator 42 sends the rising signal UP. When the input signal Vd is smaller than the output peak signal, the comparator 42 sends the down signal DN. The counter 44 raises the count value COT according to the up signal UP or down the count value COT according to the down signal DN. The digital analog converter 46 generates an output peak signal Vpeak based on the count value COT. The clock generator 40 provides the operating clock CLK1 or CLK2 to the comparator 42 to determine the operating frequency of the comparator 42, wherein the frequency of the operating clock CLK1 is higher than the frequency of the operating clock CLK2. When the input signal Vd is greater than the output peak signal Vpeak, as shown in time t1 to t2 and time t3 to t4 of FIG. 10, the comparator 42 sends the up signal UP, and the pulse generator 40 provides the working clock when receiving the rising signal UP. CLK1 is applied to the comparator 42, so that the comparator 42 has a higher operating frequency, and the count value COT is thus increased at a faster frequency, so that the output signal peak value Vpeak can quickly rise with the input signal Vin. When the input signal Vd is smaller than the output peak signal Vpeak, as shown in time t2 to t3 of FIG. 10, the comparator 42 sends the down signal DN, and when the pulse generator 40 receives the down signal DN, the working clock CLK2 is supplied to the comparator 42. Therefore, the operating frequency of the comparator 42 decreases, the count value COT will be lowered at a slow frequency, and the peak signal Vpeak is output and thus stabilized at the peak.

The above description of the preferred embodiments of the present invention is intended to be illustrative, and is not intended to limit the scope of the invention to the disclosed embodiments. It is possible to make modifications or variations based on the above teachings or learning from the embodiments of the present invention. , embodiment The principles of the present invention are described and illustrated in the actual application of the present invention in various embodiments. The technical idea of the present invention is determined by the scope of the following claims and their equals.

2‧‧‧Control IC

4‧‧‧Bridge rectifier

6‧‧‧voltage circuit

8‧‧‧ Peak Detector

10‧‧‧Ideal diode

12‧‧‧Transition circuit

14‧‧‧ square root detector

20‧‧‧Signal Peak Detector

22‧‧‧First comparator

24‧‧‧Second comparator

26‧‧‧First counter

28‧‧‧First digital analog converter

29‧‧‧Storage unit

30‧‧‧Second counter

32‧‧‧Second digital analog converter

40‧‧‧ Clock Generator

42‧‧‧ comparator

44‧‧‧ counter

46‧‧‧Digital Analog Converter

Figure 1 shows the control integrated circuit of the conventional PFC converter; Figure 2 shows the transient response of the peak signal Vpeak of Figure 1; Figure 3 shows the conventional square root detector for the PFC converter; Figure 4 shows the conventional application PFC signal peak detector; Figure 5 shows another signal peak detector used in PFC; Figure 6 shows the control integrated circuit of the present invention; Figure 7 is a waveform diagram of the signal in Figure 6; Figure 8 shows 6 is the transient response of the output peak signal Vpcak when the peak value of the input signal Vin changes; FIG. 9 is another embodiment of the peak signal detector of FIG. 6; and FIG. 10 shows the input signal Vd and the output peak signal of FIG. Waveform of Vpeak.

2‧‧‧Control IC

20‧‧‧Signal Peak Detector

22‧‧‧First comparator

24‧‧‧Second comparator

26‧‧‧First counter

28‧‧‧First digital analog converter

29‧‧‧Storage unit

30‧‧‧Second counter

32‧‧‧Second digital analog converter

Claims (16)

A control integrated circuit of a power factor correction converter, comprising a pin, receiving an input signal for the control integrated circuit to obtain the AC information of the input signal; and a signal peak detector connected to the pin to detect the input The peak of the signal generates an output peak signal of the DC information having the input signal. The signal peak detector includes: a first comparator connected to the pin, and generating a comparison signal when the input signal is greater than an internal peak signal; a counter connected to the first comparator, raised the count value outputted according to the comparison signal, and resetting the count value according to the reset signal; the first digital analog converter connecting the first comparator and the first a counter that converts the count value into the internal peak signal; a storage unit that is connected to the first counter, obtains and stores the count value from the first counter according to the sampling signal; and a second comparator that connects the pin at the input When the signal is lower than a reference voltage, the sampling signal is generated, and the reset signal is generated after the sampling signal ends; and the second digit class Converter, connected to the storage unit, generating the output signal in a peak count value stored according to the storage unit. The control integrated circuit of claim 1, wherein the operating frequency of the first comparator and the second comparator is determined by a clock. The control integrated circuit of claim 1, wherein the storage unit comprises: a switch connected to the first counter and turned on according to a sampling signal; The second counter is connected to the first counter via the switch and connected to the second digital analog converter. When the switch is turned on, the count value is obtained and stored from the first counter. A control integrated circuit of a power factor correction converter, comprising: a pin, receiving an input signal for the control integrated circuit to obtain the exchange information of the input signal; and a signal peak detector connecting the pin to detect the pin The peak value of the input signal generates an output peak signal of the DC information having the input signal. The signal peak detector includes: a comparator connected to the pin, comparing the input signal and an output peak signal to generate a rising signal or a falling signal. a counter connected to the comparator to increase or decrease the count value of the output according to the rising signal or the falling signal; and a digital analog converter connected to the comparator and the counter, and generating the input signal according to the counting value The output peak signal of the DC information; wherein the count value is increased by a first frequency and is decreased by a second frequency lower than the first frequency. The control integrated circuit of claim 4, further comprising a clock generator connected to the comparator, providing a first clock having the first frequency to determine an operating frequency of the comparator when receiving the rising signal, upon receiving The second clock having the second frequency is determined by the falling signal to determine the operating frequency of the comparator. A signal peak detector for detecting a peak value of an input signal to generate an output peak signal, the signal peak detector comprising: The first comparator generates a comparison signal when the input signal is higher than an internal peak signal; the first counter is connected to the first comparator, and the count value outputted according to the comparison signal is raised, and according to the reset signal Setting the count value; the first digital analog converter is connected to the first comparator and the first counter, and the count value is converted into the internal peak signal; the storage unit is connected to the first counter, according to the sampling signal from the first a counter obtains and stores the count value; the second comparator is connected to the first counter and the storage unit, and when the input signal is lower than a reference voltage, the sampling signal is generated, and the weight is generated after the sampling signal ends And a second digital analog converter connected to the storage unit to convert the count value stored in the storage unit into the output peak signal. The signal peak detector of claim 6, wherein the operating frequency of the first comparator and the second comparator is determined by a clock. The signal peak detector of claim 6, wherein the storage unit comprises: a switch connected to the first counter and turned on according to the sampling signal; and a second counter connected to the first counter and the second via the switch The digital analog converter acquires and stores the count value from the first counter when the switch is turned on. A signal peak detector for detecting a peak value of an input signal to generate an output peak signal, the signal peak detector comprising: a comparator for comparing the input signal and the output peak signal to generate a rising signal or a falling signal; a counter connected to the comparator to increase or decrease the count value output according to the rising signal or the falling signal; and a digital analog converter connected to the counter and the comparator to convert the count value to generate the output peak signal Wherein the count value is raised at a first frequency and is decreased at a second frequency lower than the first frequency. The signal peak detector of claim 9 further includes a clock generator connected to the comparator, and when the rising signal is received, providing a first clock having the first frequency determines an operating frequency of the comparator, Providing the second clock having the second frequency to the falling signal determines the operating frequency of the comparator. A control method for a power factor correction converter, which uses a single pin to obtain AC information and DC information of an input signal. The control method includes the following steps: (a) receiving the input signal by the pin to obtain communication information of the input signal. (b) providing a count value; (c) converting the count value to generate an internal peak signal; (d) increasing the count value when the input signal is greater than the internal peak signal; (e) when the input signal is less than the reference voltage And storing the count value; (f) generating an output peak signal of the DC information having the input signal according to the stored count value; and (g) resetting the count value after storing the count value. The control method of claim 11, wherein the step d comprises raising the count value by a frequency. A control method for a power factor correction converter uses a pin to obtain an exchange information and a DC information of an input signal, and the control method includes the following steps: (a) receiving the input signal by the pin to obtain the exchange information of the input signal; (b) providing the count value; (c) converting the count value to generate an output peak signal of the DC information having the input signal; (d) And when the input signal is greater than the output peak signal, the count value is raised by the first frequency; and (e) when the input signal is less than the output peak signal, the meter is adjusted by the second frequency less than the first frequency. Value. A signal peak detecting method for detecting a peak value of an input signal to generate an output peak signal, the signal peak detecting method comprising the steps of: (a) providing a count value; (b) converting the count value to generate an internal peak signal; c) increasing the count value when the input signal is greater than the internal peak signal; (d) storing the count value when the input signal is less than a reference voltage; (e) generating the output peak value according to the stored count value The signal; and (f) reset the count value after storing the count value. The signal peak detecting method of claim 14, wherein the step c comprises raising the count value by a frequency. A signal peak detecting method for detecting a peak value of an input signal to generate an output peak signal, the signal peak detecting method comprising the steps of: (a) providing a count value; and (b) converting the count value to generate the output peak signal; (c) increasing the count value at a first frequency when the input signal is greater than the output peak signal; (d) when the input signal is less than the output peak signal, the count value is decreased by a second frequency less than the first frequency.